#!/usr/bin/env node

const {Readable} = require('stream');
class MyReadable extends Readable {
    constructor() {
        super();
        this.#c = 'a'.charCodeAt(0);
    }

    _read() {
        this.push(String.fromCharCode(this.#c++));
        if(this.#c>'z'.charCodeAt(0)) this.push(null);
    }

    #c;
}

const mr = new MyReadable();
mr.pipe(process.stdout);